I can sympathise with the OP, it's never fun to be left hanging there, waiting for some information and receiving none.

Unfortunately the engineers' job is to troubleshoot and fix the problem and, until they have reasonable certainty that something is OK, they won't provide an ETA for a fix. In fact, if you want your head bitten off the safest way is to ask an engineer (especially a B2 engineer, in my experience) "Hey how much longer 'til it's fixed?".

It mightn't sound customer-friendly, but it's actually a key learning from past incidents. Human factors play a massive part in potential mistakes and I know of one occasion where Line engineers, under extreme pressure from the gate team and airport managers, made a potentially dangerous mistake, just because their phones wouldn't stop ringing for updates.